Organic-inorganic metal hybrid material and composition for producing organic insulator comprising the same

ABSTRACT

An organic-inorganic metal hybrid material and a composition for producing an organic insulator comprising the hybrid material. The hybrid material shows high solubility in organic solvents and monomers, and superior adhesion to substrates. In addition, the hybrid material has a high dielectric constant and a high degree of crosslinking. Based on these advantages, the hybrid material or the composition can be applied to the fabrication of various electronic devices by a wet process.

BACKGROUND OF THE INVENTION

This non-provisional application claims priority under 35 U.S.C. §119(a) on Korean Patent Application No. 2004-64690 filed on Aug. 17,2004, which is herein expressly incorporated by reference.

1. Field of the Invention

The present invention relates to an organic-inorganic metal hybridmaterial, and a composition for producing an organic insulatorcomprising the hybrid material.

2. Description of the Related Art

Most thin film transistors (TFTs) currently used in display devicesconsist of an amorphous silicon semiconductor, a silicon oxideinsulating film and metal electrodes.

With the recent advances in various materials, organic TFTs usingorganic semiconductors have been developed (U.S. Pat. No. 5,347,144).Organic thin film transistors have been researched worldwide due totheir applicability based on the new configuration. In particular, suchorganic thin film transistors have an economical advantage in that theycan be fabricated by printing processes at ambient pressure, and furtherby roll-to-roll processes using plastic substrates, instead ofconventional silicon processes, such as plasma-enhanced chemical vapordeposition (CVD).

Organic semiconductor materials for channel layers of organic thin filmtransistors are largely divided into low molecular weight materials oroligomers, e.g., melocyanine, phthalocyanine, perylene, pentacene, C60,thiophene oligomer, etc., and high molecular weight materials. LucentTechnologies Inc. and 3M Inc. developed devices with charge carriermobilities as high as 3.2˜5.0 cm²/Vs using a pentacene single crystal(3M, Mat Res. Soc. Sym. Proc. 2003, Vol. 771, L6.5.1˜L6.5.11). Inaddition, the companies reported a device having a relatively highcharge carrier mobility of 0.01˜0.1 cm²/Vs (CNRS, J. Am. Chem. Soc.,1993, Vol. 115, pp. 8716˜9721) and I_(on)/I_(off) ratio using anoligothiophene derivative. However, the fabrication of these devices ismainly dependent on vacuum processes for thin film formation.

A number of organic thin film transistors (OTFTs) fabricated using athiophene-based polymer as a high molecular weight material arereported. Although high molecular weight materials have poor devicecharacteristics when compared to low molecular weight materials, theyare advantageous in terms of their easy processability allowing them tobe processed in a large area at low costs by a solution process, such asprinting. Cambridge University and Seiko Epson Corp. have alreadyfabricated and tested high molecular weight-based organic thin filmtransistors (charge carrier mobility: 0.01˜0.02 cm²/Vs) employing apolythiophene-based material (F8T2) (see, PCT Publication WO 00/79617,Science, 2000, vol. 290, pp. 2132˜2126). Bao et. al. from LucentTechnologies Inc. disclosed the fabrication of organic thin filmtransistors (charge carrier mobility: 0.01˜0.04 cm²/Vs) employing P3HT,which is a regioregular polymer (U.S. Pat. No. 6,107,117). As notedabove, these organic thin film transistors using high molecular weightmaterials have poor TFT device characteristics, including charge carriermobility, compared to organic thin film transistors using pentacene as alow molecular weight material, but do not require a high operatingfrequency, and thus can be fabricated at low costs.

Studies on materials for insulating films which can be processed by asolution process are required in order to fabricate flexible organicthin film transistors at reduced cost, like the aforementioned organicsemiconductor materials for channel layers. Further, studies onmaterials for insulating films are actively being undertaken to improvethe performance of organic thin film transistors. Particularly, in anattempt to decrease threshold voltage, insulators having a highdielectric constant, for example, ferroelectric insulators, such asBa_(x)Sr_(1−x)TiO₃ (barium strontium titanate (BST)), Ta₂O₅, Y₂O₃, TiO₂,etc., and inorganic insulators, such as PbZr_(x)Ti_(1−x)O₃ (PZT),Bi₄Ti₃O₁₂, BaMgF₄, SrBi₂(Ta_(1−x)Nb_(x))₂O₉, Ba(Zr_(1−x)Ti_(x))O₃ (BZT),BaTiO₃, SrTiO₃, Bi₄Ti₃O₁₂, etc., have been used as materials forinorganic insulating films (U.S. Pat. No. 5,946,551; and Adv. Mater.,1999, Vol. 11, pp. 1372˜1375). However, these inorganic oxide materialsdo not have any significant advantages over conventional siliconmaterials in terms of processing.

As the application of OTFTs has been recently extended to not only LCDdisplays but also driving devices of flexible displays using an organicEL element, the OTFTs are required to have a charge carrier mobility of10 cm²/V-sec. or higher. However, since the OTFTs comprise organicinsulating films having a dielectric constant of about 3 to about 4,they require a high driving voltage (30˜50V) and a high thresholdvoltage (15˜20V).

In an attempt to increase the dielectric constant of organic insulatingfilms, dispersion of nanometer-sized ferroelectric ceramic particles inan insulating polymer is described in U.S. Pat. No. 6,586,791. But, thispatent has some problems that the ceramic particles adversely affect theformation of an organic active layer, thus decreasing charge carriermobility or increasing leakage current. To solve such problems, anadditional organic material having sufficient insulating propertiesshould be used to form a dual structure with the insulating polymer.Thus, there is a need in the art to develop an organic insulator thatshows high dielectric constant, superior insulating properties, andexcellent processability for better arrangement of organic semiconductormaterials.

OBJECT AND SUMMARY

Therefore, the present invention has been made in view of the aboveproblems, and a feature of the present invention is to provide a novelorganic-inorganic metal hybrid material which is highly soluble inorganic solvents and monomers, and has a high dielectric constant.

In accordance with one embodiment of the present invention, there isprovided an organic-inorganic metal hybrid material represented byFormula 1 below:

wherein n is an integer of 3 or less;

M is a metal atom selected from titanium, zirconium, hafnium andaluminum atoms;

R₁, R₂ and R₃ are each independently a hydrogen atom, a C_(1˜10) alkylgroup, a C_(3˜10) cycloalkyl group, a C_(6˜15) aryl group, a C_(3˜30)alkyl group or cycloalkyl group substituted with an acryloyl group, anacryloyloxy group or an epoxy group, a vinyl group, an allyl group, anacryloyloxy group, an epoxy group, a C_(1˜10) alkoxy group, OMX₁X₂X₃ (inwhich M is a metal atom selected from titanium, zirconium, hafnium andaluminum atoms; and X₁, X₂ and X₃ are each independently a hydrogenatom, a C_(1˜10) alkyl group, a C_(3˜10) cycloalkyl group, a C_(6˜15)aryl group, a C_(3˜30) alkyl group or cycloalkyl group substituted withan acryloyl group, an acryloyloxy group or an epoxy group, a vinylgroup, an allyl group, an acryloyloxy group, an epoxy group, a C_(1˜10)alkoxy group, or a halogen atom), or a halogen atom; and

R₄, R₅ and R₆ are each independently a hydrogen atom, a C_(1˜10) alkylgroup, a C_(3˜10) cycloalkyl group, a C_(6˜15) aryl group, a C_(3˜30)alkyl group or cycloalkyl group substituted with an acryloyl group, anacryloyloxy group or an epoxy group, a vinyl group, an allyl group, anacryloyloxy group, an epoxy group, a C_(1˜10) alkoxy group, OSiX₁X₂X₃(in which X₁, X₂ and X₃ are each independently a hydrogen atom, aC_(1˜10) alkyl group, a C_(3˜10) cycloalkyl group, a C_(6˜15) arylgroup, a C_(3˜30) alkyl group or cycloalkyl group substituted with anacryloyl group, an acryloyloxy group or an epoxy group, a vinyl group,an allyl group, an acryloyloxy group, an epoxy group, a C_(1˜10) alkoxygroup, or a halogen atom), or a halogen atom.

In accordance with another embodiment of the present invention, there isprovided a composition for producing an organic insulator, thecomposition comprising (i) the organic-inorganic metal hybrid material,(ii) a monomer and/or an organic polymer, and (iii) a solvent dissolvingthe components (i) and (ii).

In accordance with another embodiment of the present invention, there isprovided an electronic device fabricated using the composition.

In accordance with another embodiment of the present invention, there isprovided a method for producing an organic insulator which comprisescoating the composition on a substrate, and curing the coated substrate.

In accordance with another embodiment of the present invention, there isprovided an organic insulator produced by coating the composition on asubstrate, and curing the coated substrate.

In accordance with still another embodiment of the present invention,there is provided an organic thin film transistor comprising asubstrate, a gate electrode, an insulating layer, an organicsemiconductor layer, and a plurality of pairs of source/drain electrodeswherein the insulating layer is made of the composition.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view showing the structure of an organicthin film transistor fabricated in Example 1 of the present invention;

FIG. 2 is an infrared spectrum of an organic-inorganic metal hybridmaterial prepared in Preparative Example 1 of the present invention;

FIG. 3 is an infrared spectrum of an organic-inorganic metal hybridmaterial prepared in Preparative Example 2 of the present invention; and

FIG. 4 is a graph showing driving characteristics of an organic thinfilm transistor fabricated in Example 1 of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment of the present invention will now be described in moredetail.

An embodiment of the present invention provides an organic-inorganicmetal hybrid material represented by Formula 1 below:

wherein n is an integer of 3 or less;

M is a metal atom selected from titanium, zirconium, hafnium andaluminum atoms;

R₁, R₂ and R₃ are each independently a hydrogen atom, a C_(1˜10) alkylgroup, a C_(3˜10) cycloalkyl group, a C_(6˜15) aryl group, a C_(3˜30)alkyl group or cycloalkyl group substituted with an acryloyl group, anacryloyloxy group or an epoxy group, a vinyl group, an allyl group, anacryloyloxy group, an epoxy group, a C_(1˜10) alkoxy group, OMX₁X₂X₃ (inwhich M is a metal atom selected from titanium, zirconium, hafnium andaluminum atoms; and X₁, X₂ and X₃ are each independently a hydrogenatom, a C_(1˜10) alkyl group, a C_(3˜10) cycloalkyl group, a C_(6˜15)aryl group, a C_(3˜30) alkyl group or cycloalkyl group substituted withan acryloyl group, an acryloyloxy group or an epoxy group, a vinylgroup, an allyl group, an acryloyloxy group, an epoxy group, a C_(1˜10)alkoxy group, or a halogen atom), or a halogen atom; and

R₄, R₅ and R₆ are each independently a hydrogen atom, a C_(1˜10) alkylgroup, a C_(3˜10) cycloalkyl group, a C_(6˜15) aryl group, a C_(3˜30)alkyl group or cycloalkyl group substituted with an acryloyl group, anacryloyloxy group or an epoxy group, a vinyl group, an allyl group, anacryloyloxy group, an epoxy group, a C_(1˜10) alkoxy group, OSiX₁X₂X₃(in which X₁, X₂ and X₃ are each independently a hydrogen atom, aC_(1˜10) alkyl group, a C_(3˜10) cycloalkyl group, a C_(6˜15) arylgroup, a C_(3˜30) alkyl group or cycloalkyl group substituted with anacryloyl group, an acryloyloxy group or an epoxy group, a vinyl group,an allyl group, an acryloyloxy group, an epoxy group, a C_(1˜10) alkoxygroup, or a halogen atom), or a halogen atom.

The organic-inorganic metal hybrid material of the present invention isprepared by hydrolysis or polycondensation of at least one organosilanecompound selected from the compounds of Formulae 2a to 2c below:SiX¹X²X³X⁴  Formula 2a

wherein X¹, X², X³ and X⁴ are each independently a halogen atom, or aC_(1˜10) alkoxy group, at least one of these substituents being ahydrolysable functional group;R¹SiX¹X²X³  Formula 2b

wherein R¹ is a hydrogen atom, a C_(1˜10) alkyl group, a C_(3˜10)cycloalkyl group, a C_(6˜15) aryl group, a C_(3˜30) alkyl group orcycloalkyl group substituted with an acryloyl group, an acryloyloxygroup or an epoxy group, a vinyl group, an allyl group, an acryloyloxygroup, an epoxy group, or a C_(1˜10) alkoxy group; and X¹, X² and X³ areas defined in Formula 2c;R¹R²SiX¹X²  Formula 2c

wherein R¹ and R² are each independently a hydrogen atom, a C_(1˜10)alkyl group, a C_(3˜10) cycloalkyl group, a C_(6˜15) aryl group, aC_(3˜30) alkyl group or cycloalkyl group substituted with an acryloylgroup, an acryloyloxy group or an epoxy group, a vinyl group, an allylgroup, an acryloyloxy group, an epoxy group, or a C_(1˜10) alkoxy group;and X¹ and X² are as defined in Formula 2a,

and an organometallic compound in the presence of an acid or basecatalyst.

Organometallic compounds usable in the present invention include thosehaving superior insulating properties and a high dielectric constant,particularly, metal oxides having a dielectric constant of 4 or more.Non-limiting examples of the organometallic compound include:

1) titanium-based compounds, such as titanium (IV) n-butoxide, titanium(IV) t-butoxide, titanium (IV) ethoxide, titanium (IV) 2-ethylhexoxide,titanium (IV) isopropoxide, titanium (IV) (diisopropoxide)bis(acetylacetonate), titanium (IV) oxide bis(acetylacetonate),trichlorotris(tetrahydrofuran)titanium (III),tris(2,2,6,6-tetramethyl-3,5-heptanedionato)titanium (III), (trimethyl)pentamethyl cyclopentadienyl titanium (IV),pentamethylcyclopentadienyltitanium trichloride (IV),pentamethylcyclopentadienyltitanium trimethoxide (IV),tetrachlorobis(cyclohexylmercapto) titanium (IV),tetrachlorobis(tetrahydrofuran)titanium (IV), tetrachlorodiaminetitanium(IV), tetrakis(diethylamino)titanium (IV),tetrakis(dimethylamino)titanium (IV),bis(t-butylcyclopentadienyl)titanium dichloride,bis(cyclopentadienyl)dicarbonyl titanium (II),bis(cyclopentadienyl)titanium dichloride,bis(ethylcyclopentadienyl)titanium dichloride,bis(pentamethylcyclopentadienyl)titanium dichloride,bis(isopropylcyclopentadienyl)titanium dichloride,tris(2,2,6,6-tetramethyl-3,5-heptanedionato)oxotitanium (IV),chlorotitanium triisopropoxide, cyclopentadienyltitanium trichloride],dichlorobis(2,2,6,6-tetramethyl-3,5-heptanedionato)titanium (IV),dimethylbis(t-butylcyclopentadienyl)titanium (IV), anddi(isopropoxide)bis(2,2,6,6-tetramethyl-3,5-heptanedionato)titanium(IV);

2) zirconium-based and hafnium-based compounds, such as zirconium (IV)n-butoxide, zirconium (IV) t-butoxide, zirconium (IV) ethoxide,zirconium (IV) isopropoxide, zirconium (IV) n-propoxide, zirconium (IV)acetylacetonate, zirconium (IV) hexafluoroacetylacetonate, zirconium(IV) trifluoroacetylacetonate, tetrakis(diethylamino)zirconium,tetrakis(dimethylamino)zirconium,tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)zirconium (IV),zirconium (IV) sulfate tetrahydrate, hafnium (IV) n-butoxide, hafnium(IV) t-butoxide, hafnium (IV) ethoxide, hafnium (IV) isopropoxide,hafnium (IV) isopropoxide monoisopropylate, hafnium (IV)acetylacetonate, and tetrakis(dimethylamino)hafnium; and

3) aluminum-based compounds, such as aluminum n-butoxide, aluminumt-butoxide, aluminum s-butoxide, aluminum ethoxide, aluminumisopropoxide, aluminum acetylacetonate, aluminumhexafluoroacetylacetonate, aluminum trifluoroacetylacetonate, andtris(2,2,6,6-tetramethyl-3,5-heptanedionato)aluminum.

The acid or base catalyst used to prepare the organic-inorganic metalhybrid material of Formula 1 is preferably at least one catalystselected from the group consisting of hydrochloric acid, nitric acid,benzene sulfonic acid, oxalic acid, formic acid, potassium hydroxide,sodium hydroxide, triethylamine, sodium bicarbonate, and pyridine.

The molar ratio of the catalyst used during the hydrolysis andpolycondensation to the reactants (i.e., the organosilane-based compoundand the organic metal compound) is preferably in the range of from1:0.000001 to 1:10.

On the other hand, the molar ratio of the water used during thehydrolysis and polycondensation to the reactants is preferably in therange of 1:1 to 1:1000.

The hydrolysis and the polycondensation are preferably carried out at−40° C.˜150° C. for 0.1˜100 hours.

As preferred organic solvents usable to prepare the organic-inorganicmetal hybrid material, there may be mentioned, for example: aliphatichydrocarbon solvents, such as hexane; aromatic hydrocarbon solvents,such as anisole, mesitylene and xylene; ketone-based solvents, such asmethyl isobutyl ketone, 1-methyl-2-pyrrolidinone, acetone andcyclohexanone; ether-based solvents, such as tetrahydrofuran andisopropyl ether; acetate-based solvents, such as ethyl acetate, butylacetate and propylene glycol methyl ether acetate; alcohol-basedsolvents, such as isopropyl alcohol and butyl alcohol; amide-basedsolvents, such as dimethylacetamide and dimethylformamide; silicon-basedsolvents; and mixtures thereof.

The molecular weight of the organic-inorganic metal hybrid material thusprepared is preferably in the range of 200˜2,000, but is notparticularly limited to this range.

The present invention also provides a composition for producing anorganic insulator, comprising: i) the organic-inorganic metal hybridmaterial; ii) a monomer and/or an organic polymer; and iii) a solventdissolving the components i) and ii).

The content of the organic-inorganic metal hybrid material in thecomposition of the present invention is dependent on the kind of themonomer or the organic polymer and the solvent used, and on filmformation conditions, but is preferably in the range of 0.1˜30 parts byweight, and more preferably 0.5˜10 parts by weight, based on 100 partsby weight of the composition. When the content of the organic-inorganicmetal hybrid material exceeds 30 parts by weight, there is a problemthat the crosslinked mixture is gelled. On the other hand, when thecontent of the hybrid material is below 0.1 parts by weight, the degreeof crosslinking may be low, deteriorating the solvent resistance of athin film to be formed.

Specific examples of suitable monomers for the preparation of thecomposition according to the present invention include, but are notlimited to, methyl methacrylate, methyl acrylate, allyl methacrylate,allyl acrylate, methacrylic acid, acrylic acid, 2-hydroxyethylmethacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, glycidylacrylate, bisphenol A dimethacrylate, 2-(dimethylamino)ethylmethacrylate, 2-(dimethylamino)ethyl acrylate, ethylene glycoldimethacrylate, ethylene glycol diacrylate, trimethylolpropanetrimethacrylate, trimethylolpropane triacrylate, n-butyl methacrylate,n-butyl acrylate, stearyl methacrylate, stearyl acrylate, 1,6-hexanedioldimethacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate,2,2,2-trifluoroethyl methacrylate, 2,2,2-trifluoroethyl acrylate,2-cyanoethyl acrylate, diethylene glycol dimethacrylate, diethyleneglycol diacrylate, 2-bromoethyl acrylate, D,L-menthyl methacrylate,D,L-menthyl acrylate, 1H,1H-perfluorooctyl methacrylate,1H,1H-perfluorooctyl acrylate, 1,1,1,3,3,3-hexafluoroisopropylmethacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate,1,4-cyclohexanedimethyl 1,4-dimethacrylate, 1,4-cyclohexanedimethyl1,4-diacrylate, barium methacrylate, zinc methacrylate, methallylmethacrylate, cinnamyl methacrylate, cinnamyl acrylate, acryloxytri-N-butyltin, methacryloxypropylmethyl dichlorosilane, trimethylsilylmethacrylate, trimethylsilyl acrylate, 2-(methacryloxyl)ethylacetoacetate, 1,3-bis(3-methacryloxypropyl)tetramethyldisiloxane,3-methacrylpropyltris(vinyldimethylsiloxy)silane, vinyl acrylate, vinylacetate, vinyl chloroformate, vinyl trifluoroacetate, 2-chloroethylvinyl ether, 1,6-hexanediol divinyl ether, di(ethylene glycol) vinylether, 2-ethylhexanoic acid vinyl ester, styrene, α-methyl styrene,4-bromostyrene, 4-acetoxystyrene, 4-methoxystyrene, 2-vinylnaphthalene,2,3,4,5,6-pentafluorostyrene, 3,4-dimethoxy-1-vinylbenzene,4-vinylbiphenyl, N-vinyl-2-pyrrolidone, N-vinylcarbazole, ethyleneglycol diglycidyl ether, 1,4-butanediol diglycidyl ether,1,4-cyclohexanedimethanol diglycidyl ether, bisphenol A diglycidylether, glycerol diglycidyl ether, glycerol propoxylate triglycidylether, triphenylolmethane triglycidyl ether, 4-vinylcylcohexane dioxide,dicyclopentadiene diepoxide, diglycidyl ether,1,3-bis(3-glycidoxypropyl) tetramethyldisiloxane,1,2-cyclohexanedicarboxylic acid diglycidyl ester,1,4-bis(glycidyloxy)benzene, trimethylolpropane triglycidyl ether,3,7,14-tris[[3-(epoxypropoxy)propyl]dimethylsilyloxy]-1,3,5,7,9,11,14-heptacyclopentyltricyclo[7,3,3,15,11]heptasiloxane,N,N-diglycidylaniline, 9,9-bis[4-(glycidyloxy)phenyl]fluorene,triglycidyl isocyanurate, bis[4-(2,3-epoxy-propylthio)phenyl]sulfide,resorcinol diglycidyl ether,2,6-di(oxiran-2-ylmethyl)-1,2,3,5,6,7-hexahydropyrrolo[3,4,F]isoindole-1,3,5,7-tetraone, santolink XI-100, 1,2,7,8-diepoxyoctane,1-methyl-4-(1-methylepoxyethyl)-7-oxabicyclo[4,1,0]heptane,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, glycidylacrylate, glycidyl methacrylate,4,4′-methylenebis(N,N-diglycidylaniline),bis(3,4-epoxycyclohexylmethyl)adipate, 1,2-epoxy-4-vinylcyclohexane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like.

The content of the monomer in the composition of the present inventionis preferably in the range of 1˜40 parts by weight, and more preferably5˜20 parts by weight, based on 100 parts by weight of the composition.When the content of the monomer exceeds 40 parts by weight, there is arisk that the flexibility of a thin film to be formed is poor.Meanwhile, when the content of the monomer is less than one part byweight, the degree of crosslinking may be low, deteriorating the solventresistance of a thin film to be formed.

Non-limiting examples of suitable organic polymers for the preparationof the composition of the present invention include polyesters,polycarbonates, polyvinylalcohols, polyvinylbutyrals, polyacetals,polyarylates, polyamides, polyamidimides, polyetherimides,polyphenyleneethers, polyphenylenesulfides, polyethersulfones,polyetherketones, polyphthalamides, polyethernitriles,polyethersulfones, polybenzimidazoles, polycarbodiimides, polysiloxanes,polymethylmethacrylates, polymethacrylamides, nitrile rubbers, acrylrubbers, polyethylenetetrafluorides, epoxy resins, phenol resins,melamine resins, urea resins, polybutenes, polypentenes,poly(ethylene-co-propylene), poly(ethylene-co-butenediene),polybutadienes, polyisoprenes, poly(ethyleneco propylene diene), butylrubbers, polymethylpentenes, polystyrenes, poly(styrenebutadiene),hydrogenated poly(styrene-co-butadiene), hydrogenated polyisoprenes,hydrogenated polybutadienes, and the like.

The content of the organic polymer in the composition of the presentinvention is preferably in the range of 1˜30 parts by weight, and morepreferably 1˜20 parts by weight, based on 100 parts by weight of thecomposition. When the content of the organic polymer exceeds 30 parts byweight, there is a risk that the degree of crosslinking is low,deteriorating the solvent resistance of a thin film to be formed.

Non-limiting examples of suitable organic solvents for the preparationof the composition of the present invention include cyclohexanone,chloroform, chlorobenzene, ethyleneglycolmonomethylether,propyleneglycolmethyletheracetate, ethyllactate, toluene, xylene, methylethyl ketone, 4-heptanone, methanol, butanol, acetone,N-methylformamide, N-methylpyrrolidone, triphenylimidazole, etc. Theamount of the organic solvent used is in the range of 0˜98.9 parts byweight.

The composition of the present invention can be used to fabricate,without limitation, transistors and diodes for use in electronicdevices, including photovoltaic devices, organic light-emitting devices(LEDs), sensors, memory devices and switching devices.

The present invention also provides a method for producing an organicinsulator by coating the composition on a substrate, and curing thecoated substrate.

The coating can be carried out by spin coating, dip coating, printing,spray coating, or roll coating.

The curing is carried out by heating the coated substrate to 50° C. orhigher for at least one minute. The organic insulator thus producedshows superior insulating properties.

The present invention also provides an organic thin film transistorcomprising the organic insulator as an insulating layer. The organicthin film transistor of the present invention has a high charge carriermobility, low driving and threshold voltages, and a high I_(on)/I_(off)ratio. In addition, the organic thin film transistor of the presentinvention is highly stable in subsequent processing. In particular, agate insulating film can be formed using the composition of the presentinvention by a common wet process, such as printing or spin coating, butits performance is comparable to that of inorganic insulating filmsformed by chemical vapor deposition.

FIG. 1 shows the structure of an organic thin film transistor fabricatedin Example 1 of the present invention. The figure is provided as onepreferred embodiment of the present invention only, and various organicthin film transistors are possible so long as the object of the presentinvention is not impaired.

The substrate may be made of plastic, glass, silicon, etc.

Suitable materials for the organic active layer are those commonly usedin the art, and their specific examples include, but are not limited to,pentacenes, copper phthalocyanines, polythiophenes, polyanilines,polyacetylenes, polypyrroles, polyphenylene vinylenes, and derivativesthereof.

Suitable materials for the gate electrode and the source/drainelectrodes are metals commonly used in the art, and their specificexamples include, but are not limited to, gold, silver, aluminum,nickel, indium-tin oxides, and others.

Hereinafter, the present invention will be described in more detail withreference to the following examples. However, these examples areprovided only for illustrative purposes and are not to be construed aslimiting the scope of the present invention.

PREPARATIVE EXAMPLE 1 Preparation of Organic-Inorganic Metal HybridMaterial A

0.12 moles (4.83 g) of sodium hydroxide and 50 ml of tetrahydrofuran(THF) were placed in a reaction flask. The temperature of the flask wascooled to 0° C. After 0.48 moles (70 ml) of vinyltrimethoxysilane wasadded to the flask, the reaction temperature was gradually raised toroom temperature. The reaction mixture was allowed to react at roomtemperature for 12 hours. Volatile materials were completely evaporatedat a pressure of ca. 0.1 torr to obtain sodium silanolate as a solid.After the solid compound was dissolved in 250 ml of THF, the resultingsolution was cooled to 0° C. To the solution was slowly added 31.27 g of95% chlorotitanium triisopropoxide (Aldrich). The mixture was furtherallowed to react for 12 hours at room temperature, and was thenconcentrated at a reduced pressure of ca. 0.1 torr to remove volatilematerials. 200 ml of hexane was added to the concentrate, and theresulting mixture was filtered through celite. The obtained filtrate wasconcentrated at a reduced pressure of 0.1 torr to remove the hexane,affording a highly viscous liquid compound.

As can be seen from the IR spectrum shown in FIG. 2, strong absorptionpeaks corresponding to the Ti—O—Si bonds are observed around 960 cm⁻¹,which indicates that the organic-inorganic metal hybrid material A wasprepared.

PREPARATIVE EXAMPLE 2 Preparation of Organic-Inorganic Metal HybridMaterial B

0.12 moles (4.83 g) of sodium hydroxide and 50 ml of tetrahydrofuran(THF) were placed in a reaction flask. The temperature of the flask wascooled to 0° C. After 0.48 moles (114 ml) ofmethacryloxypropyltrimethoxysilane was added to the flask, the reactiontemperature was gradually raised to room temperature. The reactionmixture was allowed to react at room temperature for 12 hours. Volatilematerials were completely evaporated at a pressure of ca. 0.1 torr toobtain sodium silanolate as a solid. After the solid compound wasdissolved in 250 ml of THF, the resulting solution was cooled to 0° C.To the solution was slowly added 31.27 g of 95% chlorotitaniumtriisopropoxide (Aldrich). The mixture was further allowed to react for12 hours at room temperature, and was then concentrated at a reducedpressure of ca. 0.1 torr to remove volatile materials. 200 ml of hexanewas added to the concentrate, and the resulting mixture was filteredthrough celite. The obtained filtrate was concentrated at a reducedpressure of 0.1 torr to remove the hexane, affording a highly viscousliquid compound.

As can be seen from the IR spectrum shown in FIG. 3, strong absorptionpeaks corresponding to the Ti—O—Si bonds are observed around 960 cm⁻¹,which indicates that the organic-inorganic metal hybrid material B wasprepared.

PREPARATIVE EXAMPLE 3 Preparation of Composition (1) for ProducingOrganic Insulator Comprising Organic-Inorganic Metal Hybrid Material

0.3 g of the organic-inorganic metal hybrid material A prepared inPreparative Example 1, 1.0 g of trimethylolpropane trimethacrylate(Aldrich), 0.01 g of benzoyl peroxide (Aldrich), and 3.0 g ofpolyvinylphenol (Aldrich, weight-average molecular weight: 8,000) weredissolved in 27 ml of cyclohexanone to prepare a composition (1) forproducing an organic insulator.

PREPARATIVE EXAMPLE 4 Preparation of Composition (2) for ProducingOrganic Insulator Comprising Organic-Inorganic Metal Hybrid Material

0.3 g of the organic-inorganic metal hybrid material A prepared inPreparative Example 1, 0.5 g of glycidyl methacrylate (Aldrich), 0.01 gof benzoyl peroxide (Aldrich), and 2.0 g ofpoly(vinylbutyral-co-vinylalcohol-co-vinylacetate) (Aldrich) weredissolved in 10 ml of butanol to prepare a composition (2) for producingan organic insulator.

PREPARATIVE EXAMPLE 5 Preparation of Composition (1) for ProducingOrganic Insulator Comprising Organic-Inorganic Metal Hybrid Material

A composition (3) for producing an organic insulator was prepared in thesame manner as in Preparative Example 4, except that theorganic-inorganic metal hybrid material B prepared in PreparativeExample 2 was used instead of the organic-inorganic metal hybridmaterial A.

COMPARATIVE PREPARATION EXAMPLE 1 Preparation of Composition forProducing Organic Insulator Comprising No Organic-Inorganic Metal HybridMaterial

A composition for producing an organic insulator was prepared in thesame manner as in Preparative Example 3, except that noorganic-inorganic metal hybrid material was used.

EXAMPLE 1 Fabrication of Organic Thin Film Transistor by UsingOrganic-Inorganic Metal Hybrid Material

In this example, a commonly known top-contact organic thin filmtransistor was fabricated. First, A1 was deposited on a washed glasssubstrate by a vacuum deposition technique to form a gate electrodehaving a thickness of 1,500 Å. The composition (1) prepared inPreparative Example 3 was spin-coated on the gate electrode to athickness of 7,000 Å, and baked at 70° C. for 1 hour and 100° C. for 30minutes to form an insulating layer. Next, pentacene was deposited onthe insulating layer to a thickness of 700 Å by organic molecular beamdeposition (OMBD) to form an organic active layer. At this time, thedeposition was conducted under a vacuum pressure of 2×10⁻⁶ torr, asubstrate temperature of 80° C. and a deposition rate of 0.3 Å/sec.Then, source-drain electrodes were formed on the active layer with ashadow mask having a channel length of 100 μm and a channel width of 1mm to fabricate the final top-contact organic thin film transistor.

EXAMPLE 2

An organic thin film transistor was fabricated in the same manner as inExample 1, except that the composition (2) prepared in PreparativeExample 4 was used instead of the composition (1). The drivingcharacteristics of the organic thin film transistor were then measured.

EXAMPLE 3

An organic thin film transistor was fabricated in the same manner as inExample 1, except that the composition (3) prepared in PreparativeExample 5 was used instead of the composition (1). The organic thin filmtransistor was measured for the driving characteristics.

COMPARATIVE EXAMPLE 1 Fabrication of Organic Thin Film TransistorComprising No Organic-Inorganic Metal Hybrid Material

An organic thin film transistor was fabricated in the same manner as inExample 1, except that the composition prepared in ComparativePreparation Example 1 was used instead of the composition (1). Theorganic thin film transistor was measured for the drivingcharacteristics.

The current flowing between the respective source-drain electrodes ofthe organic thin film transistors fabricated in Examples 1 to 3 andComparative Example 1 was measured in response to the voltages appliedto the respective gate electrodes, and curves were plotted (FIG. 4). Themeasurement was done using a KEITHLEY semiconductor analyzer (4200-SCS).The driving characteristics of the transistors, including thresholdvoltage, I_(on)/I_(off) and charge carrier mobility, were determined inaccordance with the following procedures.

(1) Charge Carrier Mobility and Threshold Voltage

The charge carrier mobility was calculated from the slope of a graphrepresenting the relationship between (I_(SD))^(1/2) and V_(G) by thefollowing equation:

$\mu_{FET} = {({slope})^{2}\frac{2L}{C_{0}W}}$

At this time, the graph was plotted according to the following currentequations in the saturation region:

$L_{SD} = {\frac{{WC}_{0}}{2L}{\mu\left( {V_{G} - V_{T}} \right)}^{2}}$$\sqrt{I_{SD}} = {\sqrt{\frac{{\mu C}_{0}W}{2L}}\left( {V_{G} - V_{T}} \right)}$

and the slope was calculated by the following equation:

${slope} = \sqrt{\frac{{\mu C}_{0}W}{2L}}$

In the above equations (1)˜(4), I_(SD): source-drain current, μ andμ_(FET): charge carrier mobility, C_(o): capacitance of the insulatinglayer, W: channel width, L: channel length; V_(G): gate voltage, andV_(T): threshold voltage.

Threshold voltage (V_(T)) was taken from the intersection where theV_(G) axis intersects the extension of the linear portion of the graphrepresenting the relationship between (I_(SD))^(1/2) and V_(G). As theabsolute value of the threshold voltage approximates to zero, theconsumption of electric power decreases.

(2) I_(on)/I_(off) Ratio

I_(on)/I_(off) ratio can be determined from a ratio of a maximum currentin the on-state to a minimum current in the off-state, and isrepresented by the following equation:

$\frac{I_{on}}{I_{off}} = {\left( \frac{\mu}{\sigma} \right)\frac{C_{o}^{2}}{{qN}_{A}t^{2}}V_{D}^{2}}$

wherein I_(on): maximum current, I_(off): off-state leakage current, μ:charge carrier mobility, σ: conductivity of the active layer, q:electric charge, NA: electric charge density, t: thickness of theinsulating layer, C₀: capacitance of the insulating layer, and V_(D):drain voltage.

As can be seen from this equation, the larger the dielectric constantand the smaller the thickness of the dielectric film, the larger theI_(on)/I_(off) ratio. Therefore, the kind and thickness of thedielectric film are crucial factors in determining the I_(on)/I_(off)ratio. The off-state leakage current (I_(off)) is a current flowing inthe off-state, and was determined from the minimum current in theoff-state.

Measurement of Dielectric Constant:

First, each of the compositions prepared in Preparative Examples 3-5,and Comparative Preparation Example 1 was applied to an aluminumsubstrate to form a film having a thickness of 2,000 Å, and baked at 70°C. for 1 hour and at 100° C. for 30 minutes to form an insulating layer.Aluminum was deposited on the insulating layer to fabricate ametal-insulator-metal (MIM)-structured capacitor. The insulatingproperties and dielectric constant of the capacitor were measured at 20Hz. The dielectric constant was calculated by the following equation.

(3) Capacitance Per Unit Area (C₀)

The dielectric constant, which is indicative of insulating properties,was calculated from the measured capacitance C₀ according to thefollowing equation:C ₀=∈∈₀(A/d)

where A is the area of a device, d is the thickness of the insulator,and ∈ and ∈₀ are the dielectric constant of the insulator and vacuum,respectively.

The dielectric constant of the compositions prepared in PreparativeExamples 1-3 and Comparative Preparation Example 1, and the drivingcharacteristics of the organic thin film transistors fabricated usingthe respective compositions are summarized in Table 1 below.

TABLE 1 Dielectric Charge carrier constant mobility Threshold ExampleNo. (κ) (cm²/Vs) voltage (V) I_(on)/I_(off) Example 1 4.3 7.5 10 1.1 ×10⁶ Example 2 5.1 8.9 8 3.2 × 10⁶ Example 3 4.5 6.7 10 2.4 × 10⁶ Comp.Ex. 1 4.0 2.4 8 1.0 × 10⁶

As can be seen from the data shown in Table 1, the compositions(Preparative Examples 1-3) comprising the respective organic-inorganicmetal hybrid materials have higher dielectric constants than thecomposition (Comparative Preparation Example 1) comprising noorganic-inorganic metal hybrid material. In addition, the transistors(Examples 1 to 3) fabricated using the respective compositions exhibithigh charge carrier mobility while maintaining driving characteristics,i.e. threshold voltage and I_(on)/I_(off) ratio.

As apparent from the foregoing, the organic-inorganic metal hybridmaterial of the present invention can be prepared by hydrolysis orpolycondensation of an organosilane-based compound and an organometalliccompound. In addition, the composition comprising the hybrid materialcan be prepared by a solution process and is excellent in insulatingproperties. Furthermore, the organic thin film transistor fabricatedusing the composition exhibits a high charge carrier mobility, lowdriving and threshold voltages, and superior stability in subsequentprocessing.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. An organic-inorganic metal hybrid material represented by Formula 1below:

wherein n is 1; M is a metal atom selected from titanium, zirconium, andhafnium atoms; R₁, R₂ are methoxy groups, or R₃ is a vinyl group, or amethacryloxypropyl group, and R₄, R₅ and R₆ are isopropoxy groups. 2.The organic-inorganic metal hybrid material according to claim 1 whereinR₃ is vinyl.
 3. The organic-inorganic metal hybrid material according toclaim 1 wherein R₃ is methacryloxypropyl.
 4. The organic-inorganic metalhybrid material according to claim 1 wherein M is titanium.
 5. Theorganic-inorganic metal hybrid material according to claim 2 wherein Mis titanium.
 6. The organic-inorganic metal hybrid material according toclaim 3 wherein M is titanium.